insidious

adjective

Definition of insidiousnext
as in treacherous
formal causing harm in a way that is gradual or not easily noticed Most people with this insidious disease have no idea that they are infected. an insidious enemy

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Example Sentences

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Recent Examples of insidious For close to a decade, the livestreaming extremist has led a growing cohort of young men toward what’s looked like the insidious post-Trump future of the right. — Nathan Taylor Pemberton, Vanity Fair, 29 Oct. 2026 In the shadows of the Catholic church, nuns and women have long endured abuse at the hands of priests — insidious and tactful grooming, silenced by confession, and hidden through systemic cover-ups. — Jill Goldsmith, Deadline, 23 Oct. 2026 Repass cast the online conversation about irregularities in Johnson County elections as harmful and insidious. — Matthew Kelly, Kansas City Star, 22 Oct. 2026 Perhaps most controversial and, some say, the most insidious of all, is the growing adoption of digital tipping and tipping culture in general across France. — CNN Money, 4 Oct. 2026 See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
  1. treacherous
  2. subtle
  3. perfidious
  4. deceptive
  5. false
  6. misleading
  7. deceitful
  8. incorrect
Adjective
  • Adapting to these changes while navigating generational turnover can be treacherous.
    — Will Hausberg, Fortune, 4 Nov. 2026
  • Without that or a cord to stop you from picking up debris in hard-to-reach places, vacuuming won’t seem like such a treacherous chore with the V9 Motorbar.
    — Kelsey Fogarty, PC Magazine, 2 Nov. 2026
Definition of treacherous
Adjective
  • It is mounted on a wristband and detects the subtle changes in the skin caused when fingertips press against the forearm.
    — Neetika Walter, Interesting Engineering, 11 Nov. 2026
  • Trump has not been subtle about his desire to restart diplomacy with Kim.
    — Stephen E. Biegun, Foreign Affairs, 11 Nov. 2026
Definition of subtle
Adjective
  • Logan Marshall-Green as Melanthius Melanthius is a perfidious goatherd who sides with Antinous.
    — Hannah Abraham, Forbes.com, 18 July 2026
  • This is perhaps the most perfidious practice of this sort of politics.
    — David M. Drucker, Twin Cities, 3 June 2026
Definition of perfidious
Adjective
  • Voters across the country saw through the deceptive tactics utilized by super PACs, corporations, and nonprofits.
    — Letters to the Editor, The Orlando Sentinel, 11 Nov. 2026
  • The agency said undisclosed collection or use of personal information to personalize prices could violate the FTC Act’s prohibition on unfair or deceptive practices.
    — Alexandra Harrell, Footwear News, 3 Nov. 2026
Definition of deceptive
Adjective
  • Lina Attalah, a co-founder and editor-in-chief of Mada Masr, is challenging a one-year prison sentence and a fine imposed in absentia on charges of operating a website without a license and spreading false news.
    — Arkansas Online, Arkansas Online, 12 Nov. 2026
  • Numerous European carriers were hit with false bomb threats last week, including Irish airlines Aer Lingus and Ryanair, Hungarian carrier Wizz Air and Polish Airlines.
    — Aliss Higham, MSNBC Newsweek, 11 Nov. 2026
Definition of false
Adjective
  • Experts pointed to a number of possibilities for voters’ decisions, including what some characterized as successful but potentially misleading messaging by the opposition and confusion over the complex measure.
    — Lila Seidman, Los Angeles Times, 11 Nov. 2026
  • Should companies face tougher penalties for advertising misleading health benefits, especially when someone's financial security could be at stake?
    — Kurt Knutsson, FOXNews.com, 11 Nov. 2026
Definition of misleading
Adjective
  • Fielder grills Evans about this later in the film, explaining that receiving a portion of the film’s profits could jeopardize the integrity of the project and make the couple look deceitful.
    — Wesley Stenzel, Entertainment Weekly, 3 Nov. 2026
  • What readers are saying The comments reflect a strong criticism of James O'Keefe and his methods, with many labeling him as deceitful and manipulative.
    — Scott Nover, Washington Post, 22 Oct. 2026
Definition of deceitful
Adjective
  • The Department complies with all record retention obligations, and any suggestion otherwise is incorrect.
    — CBS News, CBS News, 11 Nov. 2026
  • Voting-rights advocates and election experts questioned whether errors in the unverified data contributed to potentially incorrect inactivations, the outlet reported.
    — Sam Stevenson, MSNBC Newsweek, 10 Nov. 2026
Definition of incorrect

Browse Nearby Words

inside tracks
insidious
insidiously
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Cite this Entry

“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 12 Nov. 2026.

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